TETHYAN PLATE STRUCTURES AND PETROLIFEROUS BASINS IN THE QINGHAI-TIBET PLATEAU

The Tethys in the Qinghai-Tibet Plateau is a complex structural system which is formed by multiple collisions and coherences of five crustal blocks and three plate sutured belts. Due to strong inner-continental convergences since the Cenozoic, the Tethys in the Qinghai-Tibet Plateau presently has the structural kinematic features of two structural knots, three convergence boundaries and two great shear belts. The strong convergence of boundaries combined with inner-continental uplifting, compression-shearing and extension-stripping leaded to a complex and uniform kinematic system, characterized by a thick and hot crust. The petroliferous basins in the Qinghai-Tibet Plateau can be divided into three basic types as the marine compound basin, the superposed basin of marine and continent and the continental overlapped basin etc. These basins have some notable features such as high geothermal field, low formation pressure, tight reservoirs, deep oxidized hydrocarbon boundaries and so on, which were resulted from impressions brought about the recombinations and overriding of multiple petroliferous strata, the reconstruction of multiple structural movements and the activities of hot magma.